linux-kernel - Re: [RFC PATCH V6 13/19] memory-hotplug: check page type in get_page

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Date:	Tue, 07 Aug 2012 13:31:53 +0800
From:	Wen Congyang <wency@...fujitsu.com>
To:	isimatu.yasuaki@...fujitsu.com
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
	linux-ia64@...r.kernel.org, cmetcalf@...era.com,
	rientjes@...gle.com, liuj97@...il.com, len.brown@...el.com,
	benh@...nel.crashing.org, paulus@...ba.org, cl@...ux.com,
	minchan.kim@...il.com, akpm@...ux-foundation.org,
	kosaki.motohiro@...fujitsu.com
Subject: Re: [RFC PATCH V6 13/19] memory-hotplug: check page type in get_page_bootmem

At 08/03/2012 03:49 PM, wency@...fujitsu.com Wrote:
> From: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> 
> There is a possibility that get_page_bootmem() is called to the same page many
> times. So when get_page_bootmem is called to the same page, the function only
> increments page->_count.
> 
> CC: David Rientjes <rientjes@...gle.com>
> CC: Jiang Liu <liuj97@...il.com>
> CC: Len Brown <len.brown@...el.com>
> CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> CC: Paul Mackerras <paulus@...ba.org>
> CC: Christoph Lameter <cl@...ux.com>
> Cc: Minchan Kim <minchan.kim@...il.com>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> CC: Wen Congyang <wency@...fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> ---
>  mm/memory_hotplug.c |   15 +++++++++++----
>  1 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 5f9f8c7..710e593 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -95,10 +95,17 @@ static void release_memory_resource(struct resource *res)
>  static void get_page_bootmem(unsigned long info,  struct page *page,
>  			     unsigned long type)
>  {
> -	page->lru.next = (struct list_head *) type;
> -	SetPagePrivate(page);
> -	set_page_private(page, info);
> -	atomic_inc(&page->_count);
> +	unsigned long page_type;
> +
> +	page_type = (unsigned long) page->lru.next;
> +	if (type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
> +	    type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE){

I think it should be page_type not type here.

Thanks
Wen Congyang

> +		page->lru.next = (struct list_head *) type;
> +		SetPagePrivate(page);
> +		set_page_private(page, info);
> +		atomic_inc(&page->_count);
> +	} else
> +		atomic_inc(&page->_count);
>  }
>  
>  /* reference to __meminit __free_pages_bootmem is valid

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